Roghayeh Shahshahani - Department of Biology, Faculty of science, Yazd University, Yazd, Iran
Mehri Khatami - Department of Biology, Faculty of science, Yazd University, Yazd, Iran
Mohammad Mehdi Heidari - Department of Biology, Faculty of science, Yazd University, Yazd, Iran
Ali Falahati - Department of Biology, Faculty of science, Yazd University, Yazd, Iran

Backgrounds: Antibodies are the main proteins of the immune system to identify and eliminatethe target pathogens of the infected organism that play an essential role in humoral immunity.This molecule has the potential to be used in both immunological diagnostics andimmunotherapy. The most significant property of antibodies is their ability to recognize targetswith high affinity and high specificity, which is mainly performed by CDRs. Monoclonalantibodies due to antigen-specific binding, were improved as a Research tool and diagnosticagent. In this study, monoclonal antibodies were prepared against leukemia cells and theiractivity was investigated against anti-CD۲۰.Materials and Methods: We prepared an anti-CD۲۰ antibody by PDB server and thephysicochemical analysis was performed using the protein structure prediction and Proteinliganddocking software (HADDOCK).Results: In this study, we introduced a point mutation on “۱۰۲” residue in the CDR۳ domain ofthe antibody that Tyr, a non-polar hydrophilic AA, was converted to Arg, a polar hydrophilicAA. Our result showed that the number of binding residues in the antibody-antigen binding sitewas increased. HADDOCK Z-score was -۱.۵ into -۱.۴ for mutant and native, respectively. Also,electrostatics energy calculated by HADDOCK was decreased in the mutant compared to thenative.Conclusion: Base of our results, this mutation increased the solubility and specificity, therefore,improved the binding affinity. However, further investigation is essential to clarify this binding.

Antibody, CD۲۰, CDR۳, Site direct mutagenesis